138 ANAPHYLAXIS, ALLERGY OR HYPERSENSITIVENESS 
of other immune reactions. The symptomatology of the anaphylactic 
reaction may be elicited only by the parenteral reinjection of the 
homologous antigen. 
The Nature of the Anaphylatoxin.— A noteworthy feature of ana- 
phylaxis is the similarity of symptomatology^ induced in a given 
species of animal upon reinjection with the homologous protein. It 
makes little or no difference whether the sensitizing protein be derived 
from the seeds of plants, the serum of animals, bacterial protein or 
otherwise; the train of symptoms following reinjection of the antigen 
is the same. This is interpreted to mean that the specificity of the 
reaction is resident in the products of reaction between antigen and 
antibody. It would appear that a large variety of proteins contain 
an identical poisonous group in the complex molecule which is liber- 
ated during the interaction of antigen and antibody. This is held 
to be responsible for the anaphylactic symptomatology. This poison- 
ous group or substance differs from a true bacterial toxin (exotoxin) in 
that it acts rapidly and without a latent period. Also, no specific 
antibodies capable of neutralizing the action of the anaphylatoxin have 
been prepared up to the present time. The poison is much more like 
an alkaloidal poison in all its actions than a bacterial toxin. 
ANTIANAPHYLAXIS. 
The observations of Besredka^ that desensitization, or anti-ana- 
phylaxis as it was designated, could be brought about experimentally 
by rectal injection of the homologous protein are of considerable theo- 
retical and practical importance. It was shown that animals sensi- 
tized to milk proteins and egg albumen respectively might be rendered 
antianaphylactic to reinjection three days after the rectal introduction 
of the homologous protein. Feeding the protein by mouth was also 
successful in several experiments. It is not improbable that during the 
disintegration of the protein with absorption of the fragments of diges- 
tion there is introduced into the circulation of the animal minimal 
amounts of the reactive substance, sufficient to neutralize the action of 
the anaphylactin but insufficient to induce a pronounced reaction. The 
gradual neutralization of the anaphylactin by repeated small doses of 
antigen may be resorted to in practice as a method of desensitization. 
This is not always successful, however, as Weil- has pointed out, par- 
ticularly in asthmatics.^ Huber and Koessler^ have shown that many 
asthmatics have an hypertrophied bronchial musculature, which 
seems to afford an anatomical basis for the peculiar sensitiveness in 
such cases. 
The anaphylatoxin appears to act peripherally rather than centrally' 
1 Compt. rend Soc. biol., 1911, 70, 203. = Jour. Med. Res., 1913, 29, 233. 
3 See statistics and discussion of 150 cases by Walker: Jour. Am. Med. Assn., 1917, 
69, 363. 
^ Arch. Int. Med., 192-2, 3C, GS9. 
